What is the tajwid ruling for the tanwin in instances such as the Almighty's saying: {أو لهواً انفضوا} (or amusement, then disperse) and {قوماً الله} (a people, Allah), where the tanwin precedes a dropped hamzat al-wasl during continuous recitation, and then the tanwin is vocalized with a kasra?

The nun of the silent tanwin (nunation) is vocalized with a kasra when it meets a succeeding silent letter, such as a dropped hamzat al-wasl (connecting hamza), in order to avoid the meeting of two silent letters. In such cases, the first silent letter is usually vocalized with a kasra. This applies to examples like "jazāʾan al-ḥusnā" (a good reward) and "ʿādan al-ʾūlā" (the first ʿĀd). It may be vocalized with a kasra or a ḍamma if it meets a silent letter, and it is usually vocalized with a kasra, unless a ḍamma is necessary, in which case some follow it with a ḍamma or vocalize it with a kasra.